Around half of the eligible voters cast their ballot in European elections; a bloc-wide estimate showed on Sunday, the first time turnout has risen in four decades of continent-wide voting. The increased enthusiasm was seen by some commentators as a response to challenges ranging from climate change to the rise of euro-sceptic parties.
For 27 of the 28 EU states - all except the United Kingdom - the estimate came at 51%, a European Parliament official said.
Turnout in the last European elections in 2014 hit a historic low of below 43%. The first vote in 1979 - when the EU was just nine countries - generated a peak of 62%.
Five years ago, more than 80% of voters cast their votes in Belgium and Luxembourg, where voting is obligatory, while only 13% took part in the election in the ex-communist Slovakia, according to the European Parliament's figures.
Turnout in Poland at 1500 GMT was 32.51%, double the 2014 figure, according to the country's election commission. The figure was nearly 50% in Spain, up from 34% in 2014.
Germany's Green party doubled its share of the Sunday vote, leaping into second place behind Chancellor Angela Merkel's conservatives and above the centre-left Social Democrats. France's green party also saw a surge in support.
Bas Eickhout, a Dutch member of the outgoing European Parliament with a Greens party, attributed the high turnout readings to a mobilization against a growing challenge from euroskeptic parties.
This time it was very clear that these elections really matter for Europe, Eickhout said.
There has been quite an activity on the right side saying we are going to tear down Europe, and the counter-action is now coming from a lot of progressive voters turning out and saying that we are not going to let that happen, he said.
The picture was mixed, however, as the far-right National Front came in first in France, according to exit polls.
In the run-up to the vote, Europe's biggest companies urged employees to vote, from Volkswagen unfurling a massive banner at its headquarters to Lufthansa carrying its slogan SayYesToEurope on the fuselage of an Airbus A320 to Lime offering free scooter rides to the polls.
Lobbying group BusinessEurope welcomed the higher turnout.
Europe matters to Europeans, we've seen a lively European democracy at work. We need to defend our place in the world, at a time when the EU is facing huge challenges. The world is not waiting for us, said the group's director general, Markus J Beyrer.